RU2511615C1 - Device for definition of factor of force of friction of rest - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: invention belongs to measuring devices. The device for definition of a force factor of friction of rest contains a basic platform 1. Also the device contains a box without a bottom 2, a cargo cup 3, a cord 4, a block 5 and a press platform 6 with weights 7. Thus the box without the bottom 2 is supplied with screw supports 8.

EFFECT: increased accuracy of measurement of a force factor of friction of rest.

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Description

The invention relates to measuring devices.

A known device for determining the coefficient of rest friction force, comprising a platform pivotally mounted on a bed, a measuring scale, a box without a bottom, filled with a visco-plastic material, a traction device, a support contour, guides, a shock-absorbing link (RF patent No. 2247360, G01N 19/02, 27.02 .2005 g).

A disadvantage of the known device for determining the coefficient of rest friction is the complexity of the design and the high complexity of the measurements.

A known device (selected as a prototype) for determining the coefficient of friction and shear resistance (Zenkov RL Mechanics of bulk cargo. - M .: Mechanical Engineering, 1964, p. 39 ... 47), containing a support platform, a box without a bottom, cargo cup, cord, block, pressure platform with cargo.

A disadvantage of the known device for determining the coefficient of friction force and shear resistance is the low accuracy of measurements, since loads through the pressure platform compact the test medium (bulk material) in a box without a bottom, create tangential stresses uncontrolled in magnitude on its walls that distort the initial setting of the measurement conditions - the component of the forces of moving the box without a bottom and without bulk material in it along the surface under study (steel, wood, plastic, etc.) becomes uncontrollable overestimated due to exposure to the box wall shear stresses. It is not possible to isolate this component from the value of the balancing force (the weight of the weights in the cargo cup).

The purpose of the invention is to improve the accuracy of measurements.

This goal is achieved by the fact that in the device for determining the coefficient of rest friction, containing a support platform, a box without a bottom, a cargo cup, a cord, a block, a pressure platform with loads, according to the invention, the box without a bottom is equipped with screw supports.

The invention is illustrated by drawings, where figure 1 shows a General view of a device for determining the coefficient of friction force of rest, figure 2 (node I in figure 1) shows the design of a screw support.

The device for determining the coefficient of rest friction force comprises a support platform 1, a box without a bottom 2, a cargo cup 3, a cord 4, a block 5, a pressure platform 6 with loads 7, screw supports 8.

A device for determining the coefficient of rest friction is as follows.

On the supporting platform 1 lay the investigated surface. Then, a box without a bottom 2 is installed on the latter, connected to the cargo cup 3 by a cord 4 through the block 5. After that, with the help of screw supports 8, the box without the bottom 2 is lifted above the test surface by an amount Δh less than half the minimum cross-sectional size (d _min ) of particles of the test medium ( bulk material) - Δh <d _min / 2. Next, the test medium is poured into a box without a bottom 2, leveled, a pressure platform 6 with loads 7 is installed on it. In this case, bursting forces begin to act on the wall of the box without a bottom 2. After relaxation of bursting forces and shear stresses, the screw supports 8 lift (unscrew) relative to the box without bottom 2, which is held by the test medium in its original position (without touching the test surface) due to bursting forces. Then gradually increase the load in the cargo cup 3 until the moment when the stretched cord 4 begins to displace the box without bottom 2 with the test medium on the test surface. After which the value of the coefficient of rest friction force (K _TP ) is calculated by the formula

, $${\mathrm{TO}}_{tP}=\left[\left(m_g+m_h\right)\left(\mathrm{one}-W\sqrt{2}\right)\right]/\left(m_{\mathrm{to}}+m_{\mathrm{and}\mathrm{from}}+m_{nP}+m_{gR}\right)$$

,

where m _g is the mass of weights in the cargo cup, kg;

m _h - the mass of the cargo cup, kg;

W is the coefficient of resistance to rotation of the block;

m _to - the mass of the box without bottom, kg;

_uc m - mass of the medium under investigation in a box without bottom, kg;

_np m - mass of the push platform in kg;

m _gr - the mass of goods on the pressure platform, kg.

The exclusion of contact of the box without the bottom 2 with the test surface due to its preliminary lifting by means of screw supports 8 and subsequent holding in the initial position due to bursting forces provides improved measurement accuracy, since only the lower layers of the test medium are in contact with the test surface, which does not require isolation from balancing force F of the indefinite component from the contact displacement of the box without bottom 2 on the investigated surface.

Claims (1)

A device for determining the coefficient of rest friction force, comprising a support platform, a box without a bottom, a cargo cup, a cord, a block, a pressure platform with loads, characterized in that the box without a bottom is equipped with screw supports.

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